Overweight/obesity is the second leading cause of death in the US, and is growing in prevalence at an alarming rate. Control of overweight/obesity is increasingly recognized as a high national priority because of its contribution to cardiovascular (CVD) risk factors and ultimately to CVD itself. The short-term success of behavioral interventions for weight loss has been repeatedly documented. Unfortunately, because weight re-gain is extremely common, a disappointingly, small proportion of individuals achieve long-term weight control. Of the factors that are associated with sustained weight loss, one of the most important is continued intervention with frequent contacts. We propose a multi-center, randomized, controlled trial [Weight Loss Maintenance Trial (MAINTENANCE)] to determine the effects of two innovative behavioral interventions, each designed to maintain frequent contacts, compared to a usual care control group. Overweight and obese individuals (-60% women, -40% African Americans) who are taking medication for hypertension, dyslipidemia and/or type 2 diabetes will enter a 6-month, weight loss program. Those individuals who lose at least 4 kg (N = 800) will then be randomized into one of three groups: a Personal Contact (PC) Intervention that provides monthly personal contacts with a trained interventionist, primarily via telephone; an Interactive Technology (IT) Intervention that provides frequent contacts through a state-of-the-art interactive web-based program supplemented by other communication technologies; or Usual Care (UC). The primary outcome will be weight change from the end of the initial weight loss program to the end of the 30-month weight maintenance intervention period. Other outcomes will include weight change in subgroups, prevalence of CVD risk factors, measures of behavior change, and cost of implementation. For each outcome, the PC and IT interventions will be compared to UC and, if different from UC, to each other. To successfully combat the obesity epidemic, clinicians and health care systems must have options that are effective and feasible and that can be provided to large numbers of individuals. The purpose of this proposal is to develop and test two such interventions, which, if effective, should complement ongoing efforts to stem the obesity epidemic and ultimately prevent obesity-related CVD.